不定冠词：
不定冠词"a"用来表示可数名词的单数形式，用于辅音音素前，an用于元音音素前。
如：a person, a day, an hour, an old man...
定冠词用法：
1．用于双方都知道的名词前：Please clean the classroom.
2．用于单数名词前，表示一类人或物：
The horse is a useful animal.（马是有用的动物）
This is a very hard job for the teacher.（对于老师这是一项很难的工作。）
3．用于世界上独一无二的东西前：the sun, the spring.
4．用于方位名词前：People in the west like coffee very much.
5．用于乐器名词前：play the violin
6．用于计量单位前：Gasoline is sold by the gallon.
7．形容词最高级和序数词前：
This is the easiest way to work out the problem.
He came to see me for the first time.
8．用于江河湖海山脉名称前：the Pacific，the Thames，the Rocky Mountains
9．杂志、报刊名称前：the Times，the Overseas Digest
10．用于建筑物、和组织前：the White House, the Ministry of Education
11．用于姓氏复数前，表“某某夫妇，某某一家人：the Smiths，the Greens
12．用于形容词前，表一类人 / 物：the rich, the blind
13．用于 English，Chinese，French 等名词前，表“全体国民” ：the English，the Chinese
以下情况不用冠词：
1．三餐前 breakfast，lunch，supper, ... Have you had lunch?
2．体育运动项目前 play chess,... I have no interest in tennis.
3．在由 by引出的交通工具前 by air（乘飞机），by car
4．在称呼或职位前 He has been elected president of the committee.
5．习惯用语前 at school，day by day，at table（在吃饭），go to church（做礼拜）...